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Accidentally gave my dog two Heartgard doses in 4 days. Is it safe?

Updated On September 23rd, 2025

I've given my dog two doses of heart worm medicine only 4days apart. He's a German Shepherd, 3 years old, 71 pounds, in great health. Heartgard Plus, dose 272 msg Ivermectin and 227 mg Pyrantel.

3 Answers

Most Helpful Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on January 4th, 2017

The good news is that Hartgard is a relatively safe drug, and it is difficult to overdose dogs with the medication. Typically, toxicity is worried about when the dog ingests 10-20 times the recommended dose. Your dog should be just fine :-)

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Other Answers

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    Answered By Sara Farmer, DVM

    Veterinarian

    Published on April 9th, 2018

    In general, most heartworm preventatives are very safe and it would not be harmful to give a double dose. Ivermectin and milbemycin (the active ingredients in Heartgard and Interceptor) are sometimes given daily for certain conditions. It would however help to know exactly what medication may have been given to know exactly what the risk might be. If Kobe has any other medical conditions there might be some concern and you should contact your veterinarian or the Pet Poison helpline at http://www.petpoisonhelpline.com/contact/

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    Answered By Jennifer Summerfield, DVM CPDT-KA

    Veterinarian, Certified Dog Trainer

    Published on June 18th, 2019

    Hi there. Heartgard is extremely safe, and would not harm a dog even if given multiple doses on the same day. So a second dose two days later should not cause any problems. You can just resume her normal dosing schedule next month.

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